Lunch in Pienza
In Pienza can highly recommend Trattoria Latte de Luna and Ristorate De Falco. If you want to venture outside of Pienza (but not far) head to Monticchiello for Il Ristornate La taverna di Moranda. (All the guide books mention Osteria de La Porta In Monticchiello but we have been to Taverna di Moranda 4 times and it is the best.) They have a smaller cafe next to the main restaurant. Ask to be seated in the main restaurant. A bit more expensive but you will not be disappointed. (There are stunning views of Pienza from Monticchiello too.) Also in the Val D'Orcia, in
Ristorante Osteria La Via Di Mezzo Bello
via Sconni, 53
always a good meal here too.
Have a wonderful time the Val D'Orcia. Our favorite part of Italy.
Sorry, despite the fact that San Quirico has been our home base in the Val D'Orcia for many years we have not been to Da Ciacco. We have eaten at the Osteria del Cardinale and Al Vecchio Forno a number of times. Also, for pizza (which I think may only be served in the evening, but that might have changed) is
RISTORANTE PIZZERIA LE CONTRADE | V. NUOVA 18/A/B (V. Nuova is the street just outside and opposite the North Wall gate of San Quirico.)
We tried the La Locanda Di Fonte Alla Vena last year too. Nice, traditional Tuscan food.
Also, a place you probably wouldn't think about stopping at is the truck stop restaurant outside of town; Trattoria Garibaldi. We have been here a couple of times for our Friday Fish night dinner(and last year were part of Karaoke night. That was a true local Italian experience!)
p.s. I forgot to mention in Buonconvento is the best pastry/bakery; Le Dolcezze Di Nanni. I bring home packages of their cantucci and biscotti as gifts. Their daily made baked goods sell out quickly so get there early.
San Quirico is a lovely little town with some very nice shops. Hope you get to visit there.